The present invention relates to a valve operating system for an automotive engine.
A two-intake-valve type engine, each cylinder of which has two intake valves and two exhaust valves, is disclosed in Japanese Patent Application Laid Open No. 60-1312. In the prior art, each intake (exhaust) valve is provided with a rocker arm. An actuator is provided to operatively connect both rocker arms with each other in a high engine speed range to operate both intake valves. In a low engine speed range, both the intake valves are disconnected and one of the valves is operated while the other is closed.
Such a system has advantages that an EGR ratio is reduced and the intake air speed of the engine is increased to improve combustion during a slow rotation or efficiency at low engine speed and light load on the engine.
More particularly, one of the rocker arms is removably engaged with the other by an engaging means operated by the actuator to synchronize the one rocker arm with the other. The engaging means has an engaging pin removably engaged with engaging portions of rocker arms and hydraulic control means for operating the pin.
However, the hydraulic control means is operated by a command when the engine is in predetermined operating conditions of engine speed and engine load, regardless of synchronization with the engaging timing of the pin. Thus, the pin strikes a portion other than the engaging portion of the rocker arm, which causes noises or breakdown of the pin. Further, the pin is subjected to the shearing force when the pin is engaged.